The field of this invention relates to the disarming of improvised explosive devices (IED""s), which are generally housed in hardened enclosures such as steel containers, by penetration of such containers without setting off the bomb.
In the art of bomb disablement, most terrorist-type bombs are diffused remotely by the use of disarmers or disrupters. A disrupter is a tool designed to remotely fire a variety of projectiles into a terrorist bomb to disable or dislodge the circuit and other bomb components without initiating the explosive material comprising the bomb. Water is the most common projectile; however, in order to penetrate hard containers, such as steel, which contain sensitive explosives, (e.g., nitroglycerin/nitroglycol-based dynamites), without shock initiating the explosives, water is not a suitable candidate. The shock that is caused by water which tries to penetrate the steel enclosure of the IED is normally sufficient to set it off.
Various devices are used in explosive ordinance disposal (EOD) and bomb squad environments to disable IED""s. U.S. Pat. No. 4,169,403 illustrates the use of several grams of black power electrically initiated to propel liquid out of a barrel to accomplish destruction of an IED. U.S. Pat. No. 4,957,027 discusses the versatility of the nonelectric dearmer and its use in the field of bomb disablement. The technique illustrated involves the firing of many different types of projectiles, such as clay, water, steel-lead shot, steel slugs, hardened steel projectiles, and semisolid materials to disable bombs. In the past, most bomb disrupters used water as the main projectile. The purpose of the water was to deliver a large amount of energy with controlled shock pressures. Most such disrupters are capable of firing projectiles which can penetrate steel containers, such as ammo cans, but the net result is the production of substantially high shock pressures which will shock-initiate sensitive explosives, such as dynamite.
Percussion-actuated, nonelectric (PAN) disrupters are an EOD tool designed specifically to remotely disrupt and render safe IED""s. PAN Disrupters can be used one at a time or in groups or in combination with other EOD tools. They can be sequentially initiated to attack different parts of an IED. PAN Disrupters use a shock tube propelled firing pin for cartridge initiation. Depending on the projectile fired, a PAN disrupter system is capable of impacting two or more targets inside the bomb with an isochronicity of 500 microseconds or less. Disrupters are constructed from tough, corrosion-resistant materials such as stainless steel, and are preferably heat-treated to provide a combination of maximum yield strength and toughness.
FIG. 1 illustrates a cross-section view of a PAN disrupter of a type that has been known in the art. FIG. 2 illustrates the breech end of the disrupter in greater detail. The disrupter has a barrel 10 and a breech assembly 12. The barrel is generally 24xe2x80x3 long and can have a taper so that the maximum wall thickness in the breech end 12 provides strength yet the overall disrupter weight is reduced because of the taper. The barrel length is generally an optimization between projectile performance and overall unit weight for ease of handling. The barrel 10 is chambered to receive a shell 14. Custom shells can be used or, in the situation of a PAN disrupter, standard commercial or custom-modified shotgun shells can be used. Commercial shotgun shells are generally designed to produce pressures within recommended safe maximum pressure levels of approximately 11,500-15,000 psi. The PAN disrupter shown in FIGS. 1 and 2 is designed to withstand repeated firing of loads which can produce peak chamber pressures in excess of 20,000 psi. The internal bore 16 has a polished finish which provides a seal to expanding gas pressure during shell firing and ensures uniform reproducible performance. Harder abrasive projectiles are preloaded into a protective shot cup inside the shell 14. External knurling on the barrel 10 is another feature of PAN disrupters to allow mounting to stands or robots.
The breech assembly 12 contains an internal shock tube-initiated firing pin system 20. There is no external or internal hammer/firing spring or trigger mechanism so as to provide additional protection against inadvertent discharge if the disrupter is dropped. The disrupter uses gas pressure from the shock tube 18 to actuate the firing pin assembly 20. The firing pin is retained from the shotshell primer by a spring. The firing pin 20 requires about 300 psi of gas pressure channeled through a small steel orifice to actuate the shotshell primer. A recess 24 in the rear of the breech 12 provides protection for the shock tube assembly 18 during recoil. The shock tube assembly 18 provides a quick and easy means to fasten the shock tube 18 to the disrupter. A water plug 26 isolates the water 28 which is in the barrel 10 in bore 16.
When used in the past, PAN disrupters would have an end cap at the end of the barrel 10 opposite the breech 12 such that when the shell 14 was set off with the shock tube 18, the developed pressure would propel the water and the end cap out of the bore 16 and into the target IED to disable it. While this technique proved useful for IED""s without external hardened casings such as steel ammo cans, what is now needed to handle steel-encased IED""s is a new technique which forms an object of the present invention. That technique allows penetration of hardened enclosures such as steel ammo cans without setting off sensitive explosives contained therein adjacent to the inside wall of the container. Thus, an objective of the present invention is to provide a projectile which can be fired through the hardened enclosure to defeat circuits or generally disrupt an IED without setting it off. Another object of the present invention is to provide a projectile which can accomplish this purpose which can be made from readily available materials. Yet another object of the invention is to develop a projectile that can be used alone, in tandem, or in multiple combinations with other disablement projectiles or tools. Yet another object is to provide a projectile with controlled shock pressures so that it can penetrate steel containers without fragmentation and further penetrate sensitive explosives in direct contact with the steel container without initiation. Yet another object of the invention is to teach a projectile which has a frangible component so that upon impacting the target, it separates into its constituent components to prevent plugging the entry hole made by its leading end and therefore allowing a liquid or other projectile following through to have disruption capability. Yet another object of the present invention is to provide for a penetrating projectile which can deliver listening devices, explosives or other objects for military and paramilitary applications.
A specially designed projectile is disclosed which provides an initial cruciform-shaped slit or cut, followed by the creation of a round hole into a target. This controlled entry creates a very high localized pressure during initial impact to a target for a very short duration, followed by a longer sustained lower-impact pressure. This creates a fragment-free hole into the container and can allow the projectile to penetrate sensitive explosives inside the bomb without shock-initiating or igniting the explosives. The projectile can disable bomb circuitry itself or provide a controlled entry hole to allow low-pressure water or other projectiles incapable of penetrating the steel container to enter freely. The leading end of the projectile can, with a high degree of accuracy, sever wires, destroy batteries, capacitors, and other components within a bomb or select military ordnance. The projectile can be used alone or in tandem with water or other disablement projectiles.